ISBN

The International Standard Book Number (ISBN) which is a unique numeric commercial that is actually use as a book identifier. Publishers purchase ISBN from an affiliate of this International ISBN Agency. 
An ISBN is that assigned to each edition and variation (except reprintings) of a book. For example, an e-book, a paperback and a hard cover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, and 10 digits long if assigned before 2007. The method of assigning an ISBN which is nation-based and varies from country to country, often depending on how large the publishing industry is within a country. The initial ISBN configuration of recognition [clarification needed] was generated in 1967 based upon the 9-digit Standard Book Numbering ( SBN ) created in 1966. These 10-digit ISBN format was developed by this International Organization for Standardization (ISO) and was published in 1970 as international standard ISO 2108 (the SBN code can be converted to a ten digit ISBN by prefixing it with a zero). Privately published each books some appear without an ISBN. The International ISBN agency which sometimes assigns such books ISBNs on its own initiative. Another identifier, the International Standard Serial Number (ISSN), identifies periodical publications such as magazines; and the International Standard Music Number (ISMN) that is covers for musical scores. The Standard Book Numbering (SBN) code that has a 9-digit commercial book identifier system which is created by Gordon Foster, Emeritus Professor of Statistics at Trinity College, Dublin, for that booksellers and stationers WHSmith and others in 1965. The ISBN configuration of recognition was generated in 1967 in the United Kingdom by David Whitaker (regarded as the "Father of the ISBN"[6]) and in 1968 in the United States by Emery Koltay (who later became director of the U.S. ISBN agency R.R. Bowker). An ISBN is assigned to each edition and variation (except reprintings) of a book. For example, an e-book, a paperback, and a hard cover edition of the same book would each have a different ISBN. An International Standard Book Number consists of parts (if it is a 10 digit ISBN) or 5 parts (for a 13 digit ISBN):

A 13-digit ISBN can be separated into its parts (prefix element, registration group, registration, publication and check digit), and when this is done it is customary to separate these parts with hyphens or spaces. Separating these parts (registration group, registration, publication and check digit) of a 10-digit ISBN is also done with either hyphens or spaces. Figuring out how to correctly separate a given ISBN is complicated, because most of this parts do not use a fixed number of digits. Only the term "ISBN" should be used; the terms "eISBN" and "e-ISBN" have historically been sources of confusion and should be avoided. If a book exists in one or more digital (e-book) formats, each of those formats must have its own ISBN. In other words, each of the three separate EPUB, Amazon Kindle, and PDF formats of a particular book will have its own specific ISBN. They should not share the ISBN of the paper version, and there is no generic "eISBN" which encompasses all these e-book formats for a title.